Types of wireless networks include infrastructure-based wireless networks and ad hoc wireless networks.
Ad hoc networks are self-forming networks which can operate in the absence of any fixed infrastructure, and in some cases the ad hoc network is formed entirely of mobile nodes. An ad hoc network typically includes a number of geographically-distributed, potentially mobile units, sometimes referred to as “nodes,” which are wirelessly connected to each other by one or more links (e.g., radio frequency communication channels). The nodes can communicate with each other over a wireless media without the support of an infrastructure-based or wired network. Links or connections between these nodes can change dynamically in an arbitrary manner as existing nodes move within the ad hoc network, as new nodes join or enter the ad hoc network, or as existing nodes leave or exit the ad hoc network. Because the topology of an ad hoc network can change significantly techniques are needed which can allow the ad hoc network to dynamically adjust to these changes. Due to the lack of a central controller, many network-controlling functions can be distributed among the nodes such that the nodes can self-organize and reconfigure in response to topology changes.
One characteristic of the nodes is that each node can directly communicate over a short range with nodes which are a single “hop” away. Such nodes are sometimes referred to as “neighbor nodes.” When a node transmits packets to a destination node and the nodes are separated by more than one hop (e.g., the distance between two nodes exceeds the radio transmission range of the nodes, or a physical barrier is present between the nodes), the packets can be relayed via intermediate nodes (“multi-hopping”) until the packets reach the destination node. In such situations, each intermediate node routes the packets (e.g., data and control information) to the next node along the route, until the packets reach their final destination. In a “multi-hop communication network” communications between nodes take place across multiple hops. As used herein, the term “multi-hop communication network” refers to any type of wireless network which employs routing protocols among nodes which are part of a network.
In such multi-hop networks, techniques have been proposed for transporting management information across multiple hops between nodes. As used herein, the term “management information” can refer to traffic related to the functions required for the management, control, operation and monitoring of a node or system. In transporting management information, the management information may need to be passed between one-hop neighbors, or may need to be forwarded between non-neighbor nodes. Current techniques for transporting management information typically carry the management information in fixed fields or information elements.
For instance, according to one proposed technique, a mesh data frame defined in the IEEE 802.11s draft standard can be re-used for transporting mesh management traffic. However, mesh data frames do not include fields that can be used by a node to distinguish between user and management traffic. Moreover, this solution adds complexity and overhead to the management traffic because the contents of the management frame are encapsulated in some new type of frame that must then be transported using a mesh data frame.
According to another technique proposed in the IEEE 802.11s draft standard, a new information element (IE) is proposed for use in an IEEE 802.11 action frame. The new IE can be used to transport or “tunnel” management traffic through a mesh network one hop at a time. However, an IEEE 802.11 action frame does not include address fields and mesh control fields needed to transport data across multiple hops (e.g., it is only designed for use between one hop neighbors). As such, according to this approach, management information must be packed into the body of the action frame and retrieved during transit. This is inefficient because a forwarding mesh node receiving management traffic encapsulated in an action frame must process the contents of the frame and reconstitute the action frame each time the traffic traverses a new hop. Moreover, IEEE 802.11 action frames do not include the fields required to implement other features, such as hop-by-hop encryption, which are needed to ensure the privacy of the mesh management traffic.
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